{ INFORMATICS.MCCME.RU
  Problem statement: http://informatics.mccme.ru/moodle/mod/statements/view3.php?chapterid=324
  Verdict: Accepted
}
uses SysUtils, Math;
 
type
	point=record
		x,y:longint;
	end;
 
var
	i,j,n,kk:longint;
	a:array[0..110] of point;
	ans,cx:double;
 
begin
reset(input,'input.txt');
rewrite(output,'output.txt');
read(n);
for i:=1 to n do
	read(a[i].x,a[i].y);
ans:=0;
kk:=n-1;
for i:=1 to n do
	for j:=1 to n do begin
		cx:=sqrt((a[j].x-a[i].x)*(a[j].x-a[i].x)+(a[j].y-a[i].y)*(a[j].y-a[i].y));
		ans:=max(ans,cx);
	end;
write(ans:0:15);
end.